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Bovo E, Jamrozik T, Kahn D, Karkut P, Robia SL, Zima AV. Phosphorylation of phospholamban promotes SERCA2a activation by dwarf open reading frame (DWORF). Cell Calcium 2024; 121:102910. [PMID: 38823350 DOI: 10.1016/j.ceca.2024.102910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 06/03/2024]
Abstract
In cardiac myocytes, the type 2a sarco/endoplasmic reticulum Ca-ATPase (SERCA2a) plays a key role in intracellular Ca regulation. Due to its critical role in heart function, SERCA2a activity is tightly regulated by different mechanisms, including micropeptides. While phospholamban (PLB) is a well-known SERCA2a inhibitor, dwarf open reading frame (DWORF) is a recently identified SERCA2a activator. Since PLB phosphorylation is the most recognized mechanism of SERCA2a activation during adrenergic stress, we studied whether PLB phosphorylation also affects SERCA2a regulation by DWORF. By using confocal Ca imaging in a HEK293 expressing cell system, we analyzed the effect of the co-expression of PLB and DWORF using a bicistronic construct on SERCA2a-mediated Ca uptake. Under these conditions of matched expression of PLB and DWORF, we found that SERCA2a inhibition by non-phosphorylated PLB prevails over DWORF activating effect. However, when PLB is phosphorylated at PKA and CaMKII sites, not only PLB's inhibitory effect was relieved, but SERCA2a was effectively activated by DWORF. Förster resonance energy transfer (FRET) analysis between SERCA2a and DWORF showed that DWORF has a higher relative affinity for SERCA2a when PLB is phosphorylated. Thus, SERCA2a regulation by DWORF responds to the PLB phosphorylation status, suggesting that DWORF might contribute to SERCA2a activation during conditions of adrenergic stress.
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Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA.
| | - Thomas Jamrozik
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Daniel Kahn
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Patryk Karkut
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL 60153, USA
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Zeinert R, Zhou F, Franco P, Zöller J, Lessen HJ, Aravind L, Langer JD, Sodt AJ, Storz G, Matthies D. Magnesium Transporter MgtA revealed as a Dimeric P-type ATPase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582502. [PMID: 38464158 PMCID: PMC10925321 DOI: 10.1101/2024.02.28.582502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Magnesium (Mg2+) uptake systems are present in all domains of life given the vital role of this ion. Bacteria acquire Mg2+ via conserved Mg2+ channels and transporters. The transporters are required for growth when Mg2+ is limiting or during bacterial pathogenesis, but, despite their significance, there are no known structures for these transporters. Here we report the first structure of the Mg2+ transporter MgtA solved by single particle cryo-electron microscopy (cryo-EM). Using mild membrane extraction, we obtained high resolution structures of both a homodimeric form (2.9 Å), the first for a P-type ATPase, and a monomeric form (3.6 Å). Each monomer unit of MgtA displays a structural architecture that is similar to other P-type ATPases with a transmembrane domain and two soluble domains. The dimer interface consists of contacts between residues in adjacent soluble nucleotide binding and phosphotransfer regions of the haloacid dehalogenase (HAD) domain. We suggest oligomerization is a conserved structural feature of the diverse family of P-type ATPase transporters. The ATP binding site and conformational dynamics upon nucleotide binding to MgtA were characterized using a combination of cryo-EM, molecular dynamics simulations, hydrogen-deuterium exchange mass spectrometry, and mutagenesis. Our structure also revealed a Mg2+ ion in the transmembrane segments, which, when combined with sequence conservation and mutagenesis studies, allowed us to propose a model for Mg2+ transport across the lipid bilayer. Finally, our work revealed the N-terminal domain structure and cytoplasmic Mg2+ binding sites, which have implications for related P-type ATPases defective in human disease.
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Affiliation(s)
- Rilee Zeinert
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Fei Zhou
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Pedro Franco
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Jonathan Zöller
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Henry J. Lessen
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - L. Aravind
- National Center for Biotechnology Information, National Institutes of Health, Bethesda MD 20892, USA
| | - Julian D. Langer
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Alexander J. Sodt
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Doreen Matthies
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
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3
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Šeflová J, Schwarz JA, Smith AN, Svensson B, Blackwell DJ, Phillips TA, Nikolaienko R, Bovo E, Rebbeck RT, Zima AV, Thomas DD, Van Petegem F, Knollmann BC, Johnston JN, Robia SL, Cornea RL. RyR2 Binding of an Antiarrhythmic Cyclic Depsipeptide Mapped Using Confocal Fluorescence Lifetime Detection of FRET. ACS Chem Biol 2023; 18:2290-2299. [PMID: 37769131 DOI: 10.1021/acschembio.3c00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
Hyperactivity of cardiac sarcoplasmic reticulum (SR) ryanodine receptor (RyR2) Ca2+-release channels contributes to heart failure and arrhythmias. Reducing the RyR2 activity, particularly during cardiac relaxation (diastole), is a desirable therapeutic goal. We previously reported that the unnatural enantiomer (ent) of an insect-RyR activator, verticilide, inhibits porcine and mouse RyR2 at diastolic (nanomolar) Ca2+ and has in vivo efficacy against atrial and ventricular arrhythmia. To determine the ent-verticilide structural mode of action on RyR2 and guide its further development via medicinal chemistry structure-activity relationship studies, here, we used fluorescence lifetime (FLT)-measurements of Förster resonance energy transfer (FRET) in HEK293 cells expressing human RyR2. For these studies, we used an RyR-specific FRET molecular-toolkit and computational methods for trilateration (i.e., using distances to locate a point of interest). Multiexponential analysis of FLT-FRET measurements between four donor-labeled FKBP12.6 variants and acceptor-labeled ent-verticilide yielded distance relationships placing the acceptor probe at two candidate loci within the RyR2 cryo-EM map. One locus is within the Ry12 domain (at the corner periphery of the RyR2 tetrameric complex). The other locus is sandwiched at the interface between helical domain 1 and the SPRY3 domain. These findings document RyR2-target engagement by ent-verticilide, reveal new insight into the mechanism of action of this new class of RyR2-targeting drug candidate, and can serve as input in future computational determinations of the ent-verticilide binding site on RyR2 that will inform structure-activity studies for lead optimization.
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Affiliation(s)
- Jaroslava Šeflová
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Jacob A Schwarz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Abigail N Smith
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Taylor A Phillips
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, Life Sciences Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Björn C Knollmann
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Jeffrey N Johnston
- Department of Chemistry & Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Chicago, Illinois 60153, United States
| | - Răzvan L Cornea
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
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4
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Phillips TA, Hauck GT, Pribadi MP, Cho EE, Cleary SR, Robia SL. Micropeptide hetero-oligomerization adds complexity to the calcium pump regulatory network. Biophys J 2023; 122:301-309. [PMID: 36523160 PMCID: PMC9892615 DOI: 10.1016/j.bpj.2022.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 10/24/2022] [Accepted: 12/09/2022] [Indexed: 12/16/2022] Open
Abstract
The sarco(endo)plasmic reticulum calcium ATPase (SERCA) is an ion transporter that creates and maintains intracellular calcium stores. SERCA is inhibited or stimulated by several membrane micropeptides including another-regulin, dwarf open reading frame, endoregulin, phospholamban (PLB), and sarcolipin. We previously showed that these micropeptides assemble into homo-oligomeric complexes with varying affinity. Here, we tested whether different micropeptides can interact with each other, hypothesizing that coassembly into hetero-oligomers may affect micropeptide bioavailability to regulate SERCA. We quantified the relative binding affinity of each combination of candidates using automated fluorescence resonance energy transfer microscopy. All pairs were capable of interacting with good affinity, similar to the affinity of micropeptide self-binding (homo-oligomerization). Testing each pair at a 1:5 ratio and a reciprocal 5:1 ratio, we noted that the affinity of hetero-oligomerization of some micropeptides depended on whether they were the minority or majority species. In particular, sarcolipin was able to join oligomers when it was the minority species but did not readily accommodate other micropeptides in the reciprocal experiment when it was expressed in fivefold excess. The opposite was observed for endoregulin. PLB was a universal partner for all other micropeptides tested, forming avid hetero-oligomers whether it was the minority or majority species. Increasing expression of SERCA decreased PLB-dwarf open reading frame hetero-oligomerization, suggesting that SERCA-micropeptide interactions compete with micropeptide-micropeptide interactions. Thus, micropeptides populate a regulatory network of diverse protein assemblies. The data suggest that the complexity of this interactome increases exponentially with the number of micropeptides that are coexpressed in a particular tissue.
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Affiliation(s)
- Taylor A Phillips
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Garrett T Hauck
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois.
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5
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Zhu S, Quan C, Wang R, Liang D, Su S, Rong P, Zhou K, Yang X, Chen Q, Li M, Du Q, Zhang J, Fang L, Wang HY, Chen S. The RalGAPα1-RalA signal module protects cardiac function through regulating calcium homeostasis. Nat Commun 2022; 13:4278. [PMID: 35879328 PMCID: PMC9314365 DOI: 10.1038/s41467-022-31992-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 07/07/2022] [Indexed: 11/09/2022] Open
Abstract
Sarcoplasmic/endoplasmic reticulum calcium ATPase SERCA2 mediates calcium re-uptake from the cytosol into sarcoplasmic reticulum, and its dysfunction is a hallmark of heart failure. Multiple factors have been identified to modulate SERCA2 activity, however, its regulation is still not fully understood. Here we identify a Ral-GTPase activating protein RalGAPα1 as a critical regulator of SERCA2 in cardiomyocytes through its downstream target RalA. RalGAPα1 is induced by pressure overload, and its deficiency causes cardiac dysfunction and exacerbates pressure overload-induced heart failure. Mechanistically, RalGAPα1 regulates SERCA2 through direct interaction and its target RalA. Deletion of RalGAPα1 decreases SERCA2 activity and prolongs calcium re-uptake into sarcoplasmic reticulum. GDP-bound RalA, but not GTP-bound RalA, binds to SERCA2 and activates the pump for sarcoplasmic reticulum calcium re-uptake. Overexpression of a GDP-bound RalAS28N mutant in the heart preserves cardiac function in a mouse model of heart failure. Our findings have therapeutic implications for treatment of heart failure.
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Affiliation(s)
- Sangsang Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Chao Quan
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Ruizhen Wang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Derong Liang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Shu Su
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Ping Rong
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Kun Zhou
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Xinyu Yang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Qiaoli Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Min Li
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Qian Du
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China
| | - Jingzi Zhang
- School of Medicine, Nanjing University, Nanjing, China
| | - Lei Fang
- School of Medicine, Nanjing University, Nanjing, China
| | - Hong-Yu Wang
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China.
| | - Shuai Chen
- State Key Laboratory of Pharmaceutical Biotechnology and MOE Key Laboratory of Model Animal for Disease Study, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center, Nanjing University, Nanjing, China.
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6
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Cleary SR, Fang X, Cho EE, Pribadi MP, Seflova J, Beach JR, Kekenes-Huskey PM, Robia SL. Inhibitory and stimulatory micropeptides preferentially bind to different conformations of the cardiac calcium pump. J Biol Chem 2022; 298:102060. [PMID: 35605666 PMCID: PMC9218510 DOI: 10.1016/j.jbc.2022.102060] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 05/09/2022] [Accepted: 05/13/2022] [Indexed: 12/04/2022] Open
Abstract
The ATP-dependent ion pump sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) sequesters Ca2+ in the endoplasmic reticulum to establish a reservoir for cell signaling. Because of its central importance in physiology, the activity of this transporter is tightly controlled via direct interactions with tissue-specific regulatory micropeptides that tune SERCA function to match changing physiological conditions. In the heart, the micropeptide phospholamban (PLB) inhibits SERCA, while dwarf open reading frame (DWORF) stimulates SERCA. These competing interactions determine cardiac performance by modulating the amplitude of Ca2+ signals that drive the contraction/relaxation cycle. We hypothesized that the functions of these peptides may relate to their reciprocal preferences for SERCA binding; SERCA binds PLB more avidly at low cytoplasmic [Ca2+] but binds DWORF better when [Ca2+] is high. In the present study, we demonstrated this opposing Ca2+ sensitivity is due to preferential binding of DWORF and PLB to different intermediate states that SERCA samples during the Ca2+ transport cycle. We show PLB binds best to the SERCA E1-ATP state, which prevails at low [Ca2+]. In contrast, DWORF binds most avidly to E1P and E2P states that are more populated when Ca2+ is elevated. Moreover, FRET microscopy revealed dynamic shifts in SERCA–micropeptide binding equilibria during cellular Ca2+ elevations. A computational model showed that DWORF exaggerates changes in PLB–SERCA binding during the cardiac cycle. These results suggest a mechanistic basis for inhibitory versus stimulatory micropeptide function, as well as a new role for DWORF as a modulator of dynamic oscillations of PLB–SERCA regulatory interactions.
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Affiliation(s)
- Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Xuan Fang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Ellen E Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Marsha P Pribadi
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Jordan R Beach
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Peter M Kekenes-Huskey
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
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7
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Seflova J, Habibi NR, Yap JQ, Cleary SR, Fang X, Kekenes-Huskey PM, Espinoza-Fonseca LM, Bossuyt JB, Robia SL. Fluorescence lifetime imaging microscopy reveals sodium pump dimers in live cells. J Biol Chem 2022; 298:101865. [PMID: 35339486 PMCID: PMC9048134 DOI: 10.1016/j.jbc.2022.101865] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 12/30/2022] Open
Abstract
The sodium-potassium ATPase (Na/K-ATPase, NKA) establishes ion gradients that facilitate many physiological functions including action potentials and secondary transport processes. NKA comprises a catalytic subunit (alpha) that interacts closely with an essential subunit (beta) and regulatory transmembrane micropeptides called FXYD proteins. In the heart, a key modulatory partner is the FXYD protein phospholemman (PLM, FXYD1), but the stoichiometry of the alpha-beta-PLM regulatory complex is unknown. Here, we used fluorescence lifetime imaging and spectroscopy to investigate the structure, stoichiometry, and affinity of the NKA-regulatory complex. We observed a concentration-dependent binding of the subunits of NKA-PLM regulatory complex, with avid association of the alpha subunit with the essential beta subunit as well as lower affinity alpha-alpha and alpha-PLM interactions. These data provide the first evidence that, in intact live cells, the regulatory complex is composed of two alpha subunits associated with two beta subunits, decorated with two PLM regulatory subunits. Docking and molecular dynamics (MD) simulations generated a structural model of the complex that is consistent with our experimental observations. We propose that alpha-alpha subunit interactions support conformational coupling of the catalytic subunits, which may enhance NKA turnover rate. These observations provide insight into the pathophysiology of heart failure, wherein low NKA expression may be insufficient to support formation of the complete regulatory complex with the stoichiometry (alpha-beta-PLM)2.
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Affiliation(s)
- Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Nima R Habibi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - John Q Yap
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Xuan Fang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Peter M Kekenes-Huskey
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - L Michel Espinoza-Fonseca
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Julie B Bossuyt
- Department of Pharmacology, University of California Davis, Davis, California, USA.
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
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8
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Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
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9
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Roczkowsky A, Chan BYH, Lee TYT, Mahmud Z, Hartley B, Julien O, Armanious G, Young HS, Schulz R. Myocardial MMP-2 contributes to SERCA2a proteolysis during cardiac ischaemia-reperfusion injury. Cardiovasc Res 2020; 116:1021-1031. [PMID: 31373602 DOI: 10.1093/cvr/cvz207] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 06/05/2019] [Accepted: 07/31/2019] [Indexed: 01/06/2023] Open
Abstract
AIMS Matrix metalloproteinase-2 (MMP-2) is a zinc-dependent protease which contributes to cardiac contractile dysfunction when activated during myocardial ischaemia-reperfusion (IR) injury. MMP-2 is localized to several subcellular sites inside cardiac myocytes; however, its role in the sarcoplasmic reticulum (SR) is unknown. The Ca2+ ATPase SERCA2a, which pumps cytosolic Ca2+ into the SR to facilitate muscle relaxation, is degraded in cardiac IR injury; however, the protease responsible for this is unclear. We hypothesized that MMP-2 contributes to cardiac contractile dysfunction by proteolyzing SERCA2a, thereby impairing its activity in IR injury. METHODS AND RESULTS Isolated rat hearts were subjected to IR injury in the presence or absence of the selective MMP inhibitor ARP-100, or perfused aerobically as a control. Inhibition of MMP activity with ARP-100 significantly improved the recovery of cardiac mechanical function and prevented the increase of a 70 kDa SERCA2a degradation fragment following IR injury, although 110 kDa SERCA2a and phospholamban levels appeared unchanged. Electrophoresis of IR heart samples followed by LC-MS/MS confirmed the presence of a SERCA2a fragment of ∼70 kDa. MMP-2 activity co-purified with SR-enriched microsomes prepared from the isolated rat hearts. Endogenous SERCA2a in SR-enriched microsomes was proteolyzed to ∼70 kDa products when incubated in vitro with exogenous MMP-2. MMP-2 also cleaved purified porcine SERCA2a in vitro. SERCA activity in SR-enriched microsomes was decreased by IR injury; however, this was not prevented with ARP-100. CONCLUSION This study shows that MMP-2 activity is found in SR-enriched microsomes from heart muscle and that SERCA2a is proteolyzed by MMP-2. The cardioprotective actions of MMP inhibition in myocardial IR injury may include the prevention of SERCA2a degradation.
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Affiliation(s)
- Andrej Roczkowsky
- Department of Pediatrics, University of Alberta, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, Edmonton, AB T6G 2S2, Canada.,Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Brandon Y H Chan
- Department of Pediatrics, University of Alberta, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, Edmonton, AB T6G 2S2, Canada.,Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Tim Y T Lee
- Department of Pediatrics, University of Alberta, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, Edmonton, AB T6G 2S2, Canada.,Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
| | - Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Bridgette Hartley
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Olivier Julien
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Gareth Armanious
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Richard Schulz
- Department of Pediatrics, University of Alberta, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, Edmonton, AB T6G 2S2, Canada.,Department of Pharmacology, University of Alberta, Edmonton, AB, Canada
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10
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Dimerization of SERCA2a Enhances Transport Rate and Improves Energetic Efficiency in Living Cells. Biophys J 2020; 119:1456-1465. [PMID: 32946770 DOI: 10.1016/j.bpj.2020.08.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 08/07/2020] [Accepted: 08/25/2020] [Indexed: 11/21/2022] Open
Abstract
The type 2a sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA2a) plays a key role in intracellular Ca2+ regulation in the heart. We have previously shown evidence of stable homodimers of SERCA2a in heterologous cells and cardiomyocytes. However, the functional significance of the pump dimerization remains unclear. Here, we analyzed how SERCA2a dimerization affects ER Ca2+ transport. Fluorescence resonance energy transfer experiments in HEK293 cells transfected with fluorescently labeled SERCA2a revealed increasing dimerization of Ca2+ pumps with increasing expression level. This concentration-dependent dimerization provided means of comparison of the functional characteristics of monomeric and dimeric pumps. SERCA-mediated Ca2+ uptake was measured with the ER-targeted Ca2+ sensor R-CEPIA1er in cells cotransfected with SERCA2a and ryanodine receptor. For each individual cell, the maximal ER Ca2+ uptake rate and the maximal Ca2+ load, together with the pump expression level, were analyzed. This analysis revealed that the ER Ca2+ uptake rate increased as a function of SERCA2a expression, with a particularly steep, nonlinear increase at high expression levels. Interestingly, the maximal ER Ca2+ load also increased with an increase in the pump expression level, suggesting improved catalytic efficiency of the dimeric species. Reciprocally, thapsigargin inhibition of a fraction of the population of SERCA2a reduced not only the maximal ER Ca2+ uptake rate but also the maximal Ca2+ load. These data suggest that SERCA2a dimerization regulates Ca2+ transport by improving both the SERCA2a turnover rate and catalytic efficacy. Analysis of ER Ca2+ uptake in cells cotransfected with human wild-type SERCA2a (SERCA2aWT) and SERCA2a mutants with different catalytic activity revealed that an intact catalytic cycle in both protomers is required for enhancing the efficacy of Ca2+ transport by a dimer. The data are consistent with the hypothesis of functional coupling of two SERCA2a protomers in a dimer that reduces the energy barrier of rate-limiting steps of the catalytic cycle of Ca2+ transport.
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11
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ANS Interacts with the Ca 2+-ATPase Nucleotide Binding Site. J Fluoresc 2020; 30:483-496. [PMID: 32146650 DOI: 10.1007/s10895-020-02518-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
Abstract
The binding of 8-anilino-1-naphthalene sulfonate (ANS) to the nucleotide binding domain (N-domain) of the sarcoplasmic reticulum Ca2+-ATPase (SERCA) was studied. Molecular docking predicted two ANS binding modes (BMI and BMII) in the nucleotide binding site. The molecular interaction was confirmed as the fluorescence intensity of ANS was dramatically increased when in the presence of an engineered recombinant N-domain. Molecular dynamics simulation showed BMI (which occupies the ATP binding site) as the mode that is stable in solution. The above was confirmed by the absence of ANS fluorescence in the presence of a fluorescein isothiocyanate (FITC)-labeled N-domain. Further, the labeling of the N-domain with FITC was hindered by the presence of ANS, i.e., ANS was bound to the ATP binding site. Importantly, ANS displayed a higher affinity than ATP. In addition, ANS binding led to quenching the N-domain intrinsic fluorescence displaying a FRET pattern, which suggested the existence of a Trp-ANS FRET couple. Nonetheless, the chemical modification of the sole Trp residue with N-bromosuccinimide (NBS) discarded the existence of FRET and instead indicated structural rearrangements in the nucleotide binding site during ANS binding. Finally, Ca2+-ATPase kinetics in the presence of ANS showed a partial mixed-type inhibition. The Dixon plot showed the ANS-Ca2+-ATPase complex as catalytically active, hence supporting the existence of a functional dimeric Ca2+-ATPase in sarcoplasmic reticulum vesicles. ANS may be used as a molecular platform for the development of more effective inhibitors of Ca2+-ATPase and appears to be a new fluorescent probe for the nucleotide binding site. Graphical Abstract Molecular docking of ANS to the nucleotide binding site of Ca2+-ATPase. ANS fluorescence increase reveals molecular interaction.
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12
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Arata T. Myosin and Other Energy-Transducing ATPases: Structural Dynamics Studied by Electron Paramagnetic Resonance. Int J Mol Sci 2020; 21:E672. [PMID: 31968570 PMCID: PMC7014194 DOI: 10.3390/ijms21020672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/05/2020] [Accepted: 01/06/2020] [Indexed: 02/07/2023] Open
Abstract
The objective of this article was to document the energy-transducing and regulatory interactions in supramolecular complexes such as motor, pump, and clock ATPases. The dynamics and structural features were characterized by motion and distance measurements using spin-labeling electron paramagnetic resonance (EPR) spectroscopy. In particular, we focused on myosin ATPase with actin-troponin-tropomyosin, neural kinesin ATPase with microtubule, P-type ion-motive ATPase, and cyanobacterial clock ATPase. Finally, we have described the relationships or common principles among the molecular mechanisms of various energy-transducing systems and how the large-scale thermal structural transition of flexible elements from one state to the other precedes the subsequent irreversible chemical reactions.
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Affiliation(s)
- Toshiaki Arata
- Department of Biology, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
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13
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Quan C, Li M, Du Q, Chen Q, Wang H, Campbell D, Fang L, Xue B, MacKintosh C, Gao X, Ouyang K, Wang HY, Chen S. SPEG Controls Calcium Reuptake Into the Sarcoplasmic Reticulum Through Regulating SERCA2a by Its Second Kinase-Domain. Circ Res 2019; 124:712-726. [PMID: 30566039 DOI: 10.1161/circresaha.118.313916] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
RATIONALE SPEG (Striated muscle preferentially expressed protein kinase) has 2 kinase-domains and is critical for cardiac development and function. However, it is not clear how these 2 kinase-domains function to maintain cardiac performance. OBJECTIVE To determine the molecular functions of the 2 kinase-domains of SPEG. METHODS AND RESULTS A proteomics approach identified SERCA2a (sarcoplasmic/endoplasmic reticulum calcium ATPase 2a) as a protein interacting with the second kinase-domain but not the first kinase-domain of SPEG. Furthermore, the second kinase-domain of SPEG could phosphorylate Thr484 on SERCA2a, promote its oligomerization and increase calcium reuptake into the sarcoplasmic/endoplasmic reticulum in culture cells and primary neonatal rat cardiomyocytes. Phosphorylation of SERCA2a by SPEG enhanced its calcium-transporting activity without affecting its ATPase activity. Depletion of Speg in neonatal rat cardiomyocytes inhibited SERCA2a-Thr484 phosphorylation and sarcoplasmic reticulum calcium reuptake. Moreover, overexpression of SERCA2aThr484Ala mutant protein also slowed sarcoplasmic reticulum calcium reuptake in neonatal rat cardiomyocytes. In contrast, domain mapping and phosphorylation analysis revealed that the first kinase-domain of SPEG interacted and phosphorylated its recently identified substrate JPH2 (junctophilin-2). An inducible heart-specific Speg knockout mouse model was generated to further study this SPEG-SERCA2a signal nexus in vivo. Inducible deletion of Speg decreased SERCA2a-Thr484 phosphorylation and its oligomerization in the heart. Importantly, inducible deletion of Speg inhibited SERCA2a calcium-transporting activity and impaired calcium reuptake into the sarcoplasmic reticulum in cardiomyocytes, which preceded morphological and functional alterations of the heart and eventually led to heart failure in adult mice. CONCLUSIONS Our data demonstrate that the 2 kinase-domains of SPEG may play distinct roles to regulate cardiac function. The second kinase-domain of SPEG is a critical regulator for SERCA2a. Our findings suggest that SPEG may serve as a new target to modulate SERCA2a activation for treatment of heart diseases with impaired calcium homeostasis.
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Affiliation(s)
- Chao Quan
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Min Li
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Qian Du
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Qiaoli Chen
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Hong Wang
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University, Shenzhen, China (H.W., K.F.O.Y.)
| | - David Campbell
- MRC Protein Phosphorylation and Ubiquitylation Unit (D.C.), School of Life Sciences, University of Dundee, Scotland, United Kingdom
| | - Lei Fang
- School of Medicine (L.F., B.X.), Nanjing University, China
| | - Bin Xue
- School of Medicine (L.F., B.X.), Nanjing University, China
| | - Carol MacKintosh
- Division of Cell and Developmental Biology (C.M.), School of Life Sciences, University of Dundee, Scotland, United Kingdom
| | - Xiang Gao
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Kunfu Ouyang
- Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University, Shenzhen, China (H.W., K.F.O.Y.)
| | - Hong Yu Wang
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
| | - Shuai Chen
- From the State Key Laboratory of Pharmaceutical Biotechnology, Department of Cardiology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Model Animal Research Center (C.Q., M.L., Q.D., Q.L.C., X.G., H.Y.W., S.C.), Nanjing University, China
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14
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Biological and proteomic studies of Schistosoma mansoni with decreased sensitivity to praziquantel. Comp Immunol Microbiol Infect Dis 2019; 66:101341. [DOI: 10.1016/j.cimid.2019.101341] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 07/12/2019] [Accepted: 07/26/2019] [Indexed: 12/13/2022]
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15
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Newly Discovered Micropeptide Regulators of SERCA Form Oligomers but Bind to the Pump as Monomers. J Mol Biol 2019; 431:4429-4443. [PMID: 31449798 DOI: 10.1016/j.jmb.2019.07.037] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/26/2019] [Accepted: 07/31/2019] [Indexed: 12/22/2022]
Abstract
The recently-discovered single-span transmembrane proteins endoregulin (ELN), dwarf open reading frame (DWORF), myoregulin (MLN), and another-regulin (ALN) are reported to bind to the SERCA calcium pump in a manner similar to that of known regulators of SERCA activity, phospholamban (PLB) and sarcolipin (SLN). To determine how micropeptide assembly into oligomers affects the availability of the micropeptide to bind to SERCA in a regulatory complex, we used co-immunoprecipitation and fluorescence resonance energy transfer (FRET) to quantify micropeptide oligomerization and SERCA-binding. Micropeptides formed avid homo-oligomers with high-order stoichiometry (n > 2 protomers per homo-oligomer), but it was the monomeric form of all micropeptides that interacted with SERCA. In view of these two alternative binding interactions, we evaluated the possibility that oligomerization occurs at the expense of SERCA-binding. However, even the most avidly oligomeric micropeptide species still showed robust FRET with SERCA, and there was a surprising positive correlation between oligomerization affinity and SERCA-binding. This comparison of micropeptide family members suggests that the same structural determinants that support oligomerization are also important for binding to SERCA. Moreover, the unique oligomerization/SERCA-binding profile of DWORF is in harmony with its distinct role as a PLB-competing SERCA activator, in contrast to the inhibitory function of the other SERCA-binding micropeptides.
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16
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Espinoza-Fonseca LM. Probing the effects of nonannular lipid binding on the stability of the calcium pump SERCA. Sci Rep 2019; 9:3349. [PMID: 30833659 PMCID: PMC6399444 DOI: 10.1038/s41598-019-40004-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/07/2019] [Indexed: 01/14/2023] Open
Abstract
The calcium pump SERCA is a transmembrane protein that is critical for calcium transport in cells. SERCA resides in an environment made up largely by the lipid bilayer, so lipids play a central role on its stability and function. Studies have provided insights into the effects of annular and bulk lipids on SERCA activation, but the role of a nonannular lipid site in the E2 intermediate state remains elusive. Here, we have performed microsecond molecular dynamics simulations to probe the effects of nonannular lipid binding on the stability and structural dynamics of the E2 state of SERCA. We found that the structural integrity and stability of the E2 state is independent of nonannular lipid binding, and that occupancy of a lipid molecule at this site does not modulate destabilization of the E2 state, a step required to initiate the transition toward the competent E1 state. We also found that binding of the nonannular lipid does not induce direct allosteric control of the intrinsic functional dynamics the E2 state. We conclude that nonannular lipid binding is not necessary for the stability of the E2 state, but we speculate that it becomes functionally significant during the E2-to-E1 transition of the pump.
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Affiliation(s)
- L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI, 48109, USA.
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17
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Sitsel A, De Raeymaecker J, Drachmann ND, Derua R, Smaardijk S, Andersen JL, Vandecaetsbeek I, Chen J, De Maeyer M, Waelkens E, Olesen C, Vangheluwe P, Nissen P. Structures of the heart specific SERCA2a Ca 2+-ATPase. EMBO J 2019; 38:embj.2018100020. [PMID: 30777856 DOI: 10.15252/embj.2018100020] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 12/29/2018] [Accepted: 01/10/2019] [Indexed: 12/11/2022] Open
Abstract
The sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2a (SERCA2a) performs active reuptake of cytoplasmic Ca2+ and is a major regulator of cardiac muscle contractility. Dysfunction or dysregulation of SERCA2a is associated with heart failure, while restoring its function is considered as a therapeutic strategy to restore cardiac performance. However, its structure has not yet been determined. Based on native, active protein purified from pig ventricular muscle, we present the first crystal structures of SERCA2a, determined in the CPA-stabilized E2-AlF4- form (3.3 Å) and the Ca2+-occluded [Ca2]E1-AMPPCP form (4.0 Å). The structures are similar to the skeletal muscle isoform SERCA1a pointing to a conserved mechanism. We seek to explain the kinetic differences between SERCA1a and SERCA2a. We find that several isoform-specific residues are acceptor sites for post-translational modifications. In addition, molecular dynamics simulations predict that isoform-specific residues support distinct intramolecular interactions in SERCA2a and SERCA1a. Our experimental observations further indicate that isoform-specific intramolecular interactions are functionally relevant, and may explain the kinetic differences between SERCA2a and SERCA1a.
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Affiliation(s)
- Aljona Sitsel
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus C, Denmark
| | | | - Nikolaj Düring Drachmann
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark
| | - Rita Derua
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,SyBioMa, KU Leuven, Leuven, Belgium
| | - Susanne Smaardijk
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Jacob Lauwring Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | | | - Jialin Chen
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Etienne Waelkens
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.,SyBioMa, KU Leuven, Leuven, Belgium
| | - Claus Olesen
- Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark .,Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Peter Vangheluwe
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Poul Nissen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark .,Center for Membrane Proteins in Cells and Disease - PUMPkin, Danish National Research Foundation, Aarhus C, Denmark.,Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus C, Denmark
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18
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Targeting protein-protein interactions for therapeutic discovery via FRET-based high-throughput screening in living cells. Sci Rep 2018; 8:12560. [PMID: 30135432 PMCID: PMC6105598 DOI: 10.1038/s41598-018-29685-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/16/2018] [Indexed: 01/16/2023] Open
Abstract
We have developed a structure-based high-throughput screening (HTS) method, using time-resolved fluorescence resonance energy transfer (TR-FRET) that is sensitive to protein-protein interactions in living cells. The membrane protein complex between the cardiac sarcoplasmic reticulum Ca-ATPase (SERCA2a) and phospholamban (PLB), its Ca-dependent regulator, is a validated therapeutic target for reversing cardiac contractile dysfunction caused by aberrant calcium handling. However, efforts to develop compounds with SERCA2a-PLB specificity have yet to yield an effective drug. We co-expressed GFP-SERCA2a (donor) in the endoplasmic reticulum membrane of HEK293 cells with RFP-PLB (acceptor), and measured FRET using a fluorescence lifetime microplate reader. We screened a small-molecule library and identified 21 compounds (Hits) that changed FRET by >3SD. 10 of these Hits reproducibly alter SERCA2a-PLB structure and function. One compound increases SERCA2a calcium affinity in cardiac membranes but not in skeletal, suggesting that the compound is acting specifically on the SERCA2a-PLB complex, as needed for a drug to mitigate deficient calcium transport in heart failure. The excellent assay quality and correlation between structural and functional assays validate this method for large-scale HTS campaigns. This approach offers a powerful pathway to drug discovery for a wide range of protein-protein interaction targets that were previously considered “undruggable”.
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19
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Raguimova ON, Smolin N, Bovo E, Bhayani S, Autry JM, Zima AV, Robia SL. Redistribution of SERCA calcium pump conformers during intracellular calcium signaling. J Biol Chem 2018; 293:10843-10856. [PMID: 29764938 PMCID: PMC6052202 DOI: 10.1074/jbc.ra118.002472] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/01/2018] [Indexed: 11/06/2022] Open
Abstract
The conformational changes of a calcium transport ATPase were investigated with molecular dynamics (MD) simulations as well as fluorescence resonance energy transfer (FRET) measurements to determine the significance of a discrete structural element for regulation of the conformational dynamics of the transport cycle. Previous MD simulations indicated that a loop in the cytosolic domain of the SERCA calcium transporter facilitates an open-to-closed structural transition. To investigate the significance of this structural element, we performed additional MD simulations and new biophysical measurements of SERCA structure and function. Rationally designed in silico mutations of three acidic residues of the loop decreased SERCA domain-domain contacts and increased domain-domain separation distances. Principal component analysis of MD simulations suggested decreased sampling of compact conformations upon N-loop mutagenesis. Deficits in headpiece structural dynamics were also detected by measuring intramolecular FRET of a Cer-YFP-SERCA construct (2-color SERCA). Compared with WT, the mutated 2-color SERCA shows a partial FRET response to calcium, whereas retaining full responsiveness to the inhibitor thapsigargin. Functional measurements showed that the mutated transporter still hydrolyzes ATP and transports calcium, but that maximal enzyme activity is reduced while maintaining similar calcium affinity. In live cells, calcium elevations resulted in concomitant FRET changes as the population of WT 2-color SERCA molecules redistributed among intermediates of the transport cycle. Our results provide novel insights on how the population of SERCA pumps responds to dynamic changes in intracellular calcium.
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Affiliation(s)
- Olga N Raguimova
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Nikolai Smolin
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Elisa Bovo
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Siddharth Bhayani
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Joseph M Autry
- the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Aleksey V Zima
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
| | - Seth L Robia
- From the Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois 60153 and
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20
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Abstract
The calcium pump (a.k.a. Ca2+-ATPase or SERCA) is a membrane transport protein ubiquitously found in the endoplasmic reticulum (ER) of all eukaryotic cells. As a calcium transporter, SERCA maintains the low cytosolic calcium level that enables a vast array of signaling pathways and physiological processes (e.g. synaptic transmission, muscle contraction, fertilization). In muscle cells, SERCA promotes relaxation by pumping calcium ions from the cytosol into the lumen of the sarcoplasmic reticulum (SR), the main storage compartment for intracellular calcium. X-ray crystallographic studies have provided an extensive understanding of the intermediate states that SERCA populates as it progresses through the calcium transport cycle. Historically, SERCA is also known to be regulated by small transmembrane peptides, phospholamban (PLN) and sarcolipin (SLN). PLN is expressed in cardiac muscle, whereas SLN predominates in skeletal and atrial muscle. These two regulatory subunits play critical roles in cardiac contractility. While our understanding of these regulatory mechanisms are still developing, SERCA and PLN are one of the best understood examples of peptide-transporter regulatory interactions. Nonetheless, SERCA appeared to have only two regulatory subunits, while the related sodium pump (a.k.a. Na+, K+-ATPase) has at least nine small transmembrane peptides that provide tissue specific regulation. The last few years have seen a renaissance in our understanding of SERCA regulatory subunits. First, structures of the SERCA-SLN and SERCA-PLN complexes revealed molecular details of their interactions. Second, an array of micropeptides concealed within long non-coding RNAs have been identified as new SERCA regulators. This chapter will describe our current understanding of SERCA structure, function, and regulation.
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21
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Bidwell PA, Haghighi K, Kranias EG. The antiapoptotic protein HAX-1 mediates half of phospholamban's inhibitory activity on calcium cycling and contractility in the heart. J Biol Chem 2017; 293:359-367. [PMID: 29150445 DOI: 10.1074/jbc.ra117.000128] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/17/2017] [Indexed: 12/25/2022] Open
Abstract
The antiapoptotic protein HAX-1 (HS-associated protein X-1) localizes to sarcoplasmic reticulum (SR) in the heart and interacts with the small membrane protein phospholamban (PLN), inhibiting the cardiac sarco/endoplasmic reticulum calcium ATPase 2a (SERCA2a) in the regulation of overall calcium handling and heart muscle contractility. However, because global HAX-1 deletion causes early lethality, how much endogenous HAX-1 contributes to PLN's inhibitory activity on calcium cycling is unknown. We therefore generated a cardiac-specific and inducible knock-out mouse model. HAX-1 ablation in the adult heart significantly increased contractile parameters and calcium kinetics, associated with increased SR calcium load. These changes occurred without any changes in the protein expression of SERCA2a, PLN, and ryanodine receptor or in the PLN phosphorylation status. The enhanced calcium cycling in the HAX-1-depleted heart was mediated through increases in the calcium affinity of SERCA2a and reduced PLN-SERCA2a binding. Comparison of the HAX-1 deletion-induced stimulatory effects with those elicited by PLN ablation indicated that HAX-1 mediates ∼50% of the PLN-associated inhibitory effects in the heart. Stimulation with the inotropic and lusitropic agent isoproterenol eliminated the differences among wild-type, HAX-1-deficient, and PLN-deficient hearts, and maximally stimulated contractile and calcium kinetic parameters were similar among these three groups. Furthermore, PLN overexpression in the HAX-1-null cardiomyocytes did not elicit any inhibitory effects, indicating that HAX-1 may limit PLN activity. These findings suggest that HAX-1 is a major mediator of PLN's inhibitory activity and a critical gatekeeper of SR calcium cycling and contractility in the heart.
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Affiliation(s)
- Philip A Bidwell
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Kobra Haghighi
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Evangelia G Kranias
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267; Department of Molecular Biology, Center of Basic Research, Biomedical Research Foundation, Academy of Athens, 115 27 Athens, Greece.
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Smeazzetto S, Armanious GP, Moncelli MR, Bak JJ, Lemieux MJ, Young HS, Tadini-Buoninsegni F. Conformational memory in the association of the transmembrane protein phospholamban with the sarcoplasmic reticulum calcium pump SERCA. J Biol Chem 2017; 292:21330-21339. [PMID: 29081402 DOI: 10.1074/jbc.m117.794453] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/19/2017] [Indexed: 11/06/2022] Open
Abstract
The sarcoplasmic reticulum Ca2+-ATPase SERCA promotes muscle relaxation by pumping calcium ions from the cytoplasm into the sarcoplasmic reticulum. SERCA activity is regulated by a variety of small transmembrane peptides, most notably by phospholamban in cardiac muscle and sarcolipin in skeletal muscle. However, how phospholamban and sarcolipin regulate SERCA is not fully understood. In the present study, we evaluated the effects of phospholamban and sarcolipin on calcium translocation and ATP hydrolysis by SERCA under conditions that mimic environments in sarcoplasmic reticulum membranes. For pre-steady-state current measurements, proteoliposomes containing SERCA and phospholamban or sarcolipin were adsorbed to a solid-supported membrane and activated by substrate concentration jumps. We observed that phospholamban altered ATP-dependent calcium translocation by SERCA within the first transport cycle, whereas sarcolipin did not. Using pre-steady-state charge (calcium) translocation and steady-state ATPase activity under substrate conditions (various calcium and/or ATP concentrations) promoting particular conformational states of SERCA, we found that the effect of phospholamban on SERCA depends on substrate preincubation conditions. Our results also indicated that phospholamban can establish an inhibitory interaction with multiple SERCA conformational states with distinct effects on SERCA's kinetic properties. Moreover, we noted multiple modes of interaction between SERCA and phospholamban and observed that once a particular mode of association is engaged it persists throughout the SERCA transport cycle and multiple turnover events. These observations are consistent with conformational memory in the interaction between SERCA and phospholamban, thus providing insights into the physiological role of phospholamban and its regulatory effect on SERCA transport activity.
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Affiliation(s)
- Serena Smeazzetto
- From the Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy and
| | - Gareth P Armanious
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Maria Rosa Moncelli
- From the Department of Chemistry "Ugo Schiff," University of Florence, 50019 Sesto Fiorentino, Italy and
| | - Jessi J Bak
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Howard S Young
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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